Anode assembly for electrolytic cell



Jan. 9, 1962 F. J. KRENZKE 3,016,343

ANoDr: ASSEMBLY FOR ELECTROLYTIC CELL Filed oct. 1e, 1958 F 2 INVENTOR.

Freo/J Kre/73k@ United States Patented Jan. 9, 1962 3,016,343 ANDE AdSEMBLY FDR ELECTRQLYTIC CELL Fred J. Krenzlre, Lahe Jackson, Tex., assigner to The Dow Chemical Company, Midland, Mich., a corpora tion of Delaware Filed (ict. 16, 1953, Ser. No. 767,572 2 Claims. (Cl. 20d-2%) This invention relates to anodes for use in electric furnaces and electrolytic cells and particularly to anodes in which two elongated segments are joined together in end-to-end relationship. The invention is particularly well adapted to usage with anodes having non-circular transverse cross-sectional configuration.

In the operation of some electrolytic cells used in the production of light metals, for example, it is very desirable to use a consumable anode of graphite or carbon which has a square or rectangular transverse cross-sectional coniiguration. Since the lower end of the anode is consumed during the operation of the cell, provision is made for advancing the anode downwardly through a suitable close fitting aperture in the cell cover. In such a situation it is, of course, necessary that the anode corners of the joined segments be axially aligned.

Further, if the anodes are to function well in the furnace or electrolytic cell, the electrical resistance of the joint between the segments must have a low value. A suitable resistance value of a joint between segments is considered to be the resistance of an anode segment having a length of six inches or less.

When anode segments of non-circular cross-section are threaded in the usual manner, it has been found to be impractical to achieve both corner alignment and low resistance joints because the pressure needed to make the ylow resistance joint seldom, if ever, occurs at the point along the threads where the corners of the segments are perfectly aligned.

The result has been that even though electrolytic cells which are designed for use with anodes of square or rectangular cross section are very desirable from the standpoint of output capacity per unit of time, their use has been limited because of the diiiiculty in adding anode segments to replace the consumed part of the anode.

Accordingly, a principal object of this invention is to provide an improved segmented carbon or graphite electrode.

Another object of this invention is to provide an irnproved carbon or graphite electrode which is composed of two or more elongated segments of non-circuiar transverse cross-sectional configuration which are joined together in an end-to-end relationship. v

The invention, as well as additional objects and advantages thereof, will best be understood when the following detailed description is read in connection with the accompanying drawings, in which:

FIG. l is a plan view of a segmented anode and joining tool in accordance with this invention.

FIG. 2 is a side elevational View, taken along the line 2-2 of FIG. l, of a segmented anode and joining tool in accordance with this invention;

FIG. 3 is a side elevational view, on an enlarged scale, of the joining nipple shown in FIG. 2; and

FIG. 4 is a plan view of the nipple shown in FIG. 3.

Referring to the drawings, particularly to FG. l, there is shown a segmented electrode or anode, indicated gen-` erally by the numeral 10, which comprises a lower segment 12 of square transverse cross-sectional configuration and of uniform width and thickness along its length and an upper anode or electrode segment 14 of substantially identical side dimensions and length as the anode or electrode segment 12.

The segments 12 and 14' are joined together by a nipple, indicated generally by the numeral 16, which is shown in more detail in FIGS. 3 and 4.

As illustrated, the segment 14 has an axially aligned bore 18 extending through the entire length of the block, the center of the bore 18 being along the intersection of transverse diagonals (not shown) of the block. The segment 14 contains threaded counter bores 2l), 22 at its top and bottom ends, respectively. The counter bores 20, 22 are coaxial with the bore 18 and are conveniently though not necessarily, of the samediameter. 'Ille threads of each counter bore 20 or 22 are of the same hand (both right hand threads or both left hand threads, for example) but are of different pitch. The pitch of the threads in the counter bore 20, for example, have slightly less pitch than the threads of the counter bore 22. The anode or electrode segment 12 contains a threaded bore 24 at its upper end 26 which is of the same diameter and depth as the counter bore 20. The threads 23 of the bore 24 are, for example, of the same pitch and hand as the threads 30 of the counter bore 2li (and of less pitch than the threads y 32 of the counter bore 22).

The nipple 16 is of generally cylindrical configuration with threads on both the upper and lower part of the side walls thereof. The threads 34 on the upper wall and the threads '36 on the lower side wall are, like the threads 3d and 32, of the same hand and, usually, of the same diameter, but different pitch. The pitch of the threads 34 are, for example, the same as that of the threads 32 while the pitch of the threads 36 is the same as that of the threads 2S. The top 38 o-f the nipple 16 contains an axially aligned recess 40 of square or rectangular transverse cross-sectional configuration.

In operation the nipple 16 is screwed almost half way into the threaded bore 24 in the segment 12 and then the end of the segment 14. which contains the threaded bore 22 is threaded onto the protruding end of the nipple 16 until the anode segments 12 and 14 almost meet and the corners of the segments 12 and 1d are axially aligned with respect to each other.

A wrench a2 having an elbow-like configuration and a lower end adapted to mate with the recess 40 of the nipple 16 is inserted through .the bore 18 of the segment 14 and coupled to the nipple 16. The wrench 42 is then rotated to revolve the nipple 16, drawing together the segments 12 and 14 because of the differential in the pitch between the threads 34 and 36. The threads 34 have a slightly larger pitch than the threads 36, so a large mechanical advantage is achieved to pull together the segments 12 and 14 as the nipple is tightened. In one anode assembly made in accordance with this invention two graphite elec trode segments having a 20" by 20 cross section and which are approximately four feet in length are joined together. The bore 13 is 3 inches in diameter' and the threaded counter bores 2li, 22 and 2d are about 8 inches deep. The nipple 16, made of graphite, is 7.25 inches in diameter by 13.75 Ainches long and has two sets of threads (each set running 6 inches along the nipple). The threads 3d are Acme threads having 2% turns per inch with a thread depth of .157 inch. The threads 36 are similar but have a pitch of only 2 threads per inch. The recess or socket dit is- 2 inches square and 3 inches deep.

It has been found that pressure of about pounds per square inch between the segments is necessary in order to get a satisfactory low electrical resistance joint between the segments. For 20 inch by 20 inch electrodes this amounts to a load on the nipple of 32,000 pounds. The development of such a loading would usually require the mechanical advantage of a ine thread. Fine threads, however, cannot be used in this application Where soft, flaky carbon or `graphite is used as the anode material because the fine threads would strip out under pressure. Thread stripping would be especially probable when the upper segment is started to be threaded onto the nipple, since during that operation the massive electrode segment must be rotated.

The use of two coarse threads o\f slightly dierent pitch and of the same hand offers the necessary mechanical advantage, yet the threads are sturdy enough to prevent stripping when the segments are joined.

yWhile the drawing illustrates a bottom anode segment 12 which is solid except for the socket bore 24%, other segments, like ythe segment 14, may be attached end-on-end to provide either a very elongated anode or to replace other segments as they are consumed during the operation of the cell.

Anode segments joined together in accordance with the teachings of this invention provide an electrical resistance across the joint having less electrical resistance than a six inch length of solid anode of the same cross-sectional configuration.

I claim:

1. A composite anode comprising a pair of axially aligned elongated block-like consumable graphitic elec- `trodes each having the same outer surface configuration along :their entire length and having flat end surfaces, each electrode having a bore extending axially therethrough from end to end, a threaded counter bore extending inwardly `from each end of each electrode, the threads of the counter bores of corresponding ends of the electrodes being identical, the pitch of the threads of the counter bore at one end of each electrode being inthe same direction of rotation but different in pitch than the pitch of the thread of the counter bore at the other end of the electrode, a threaded solid graphitic nipple, said nipple having an instrument receiving depression in one end thereof, the threads of the nipple being `in two groups, one group being adapted to mate with the threads in the counter bore at one end of said electrode and the other group being adapted to mate with the threads at the opposite end ofthe said electrode, said nipple being threaded into a counter bore in each of said pair of electrodes with the end surfaces of the electrodes in contact and the outer surfaces of the electrodes aligned to form a substantially continuous outer surface Valong said joined electrodes.

2. A composite anode in accordance with claim 1, wherein each of said electrodes is of gene-rally rectangular transverse cross-sectional configuration.

References Cited in the le of this patent UNITED STATES PATENTS 1,588,128 YMontgomery June 8, 1926 1,850,515 Peltz Mar. 22, 1932.

FOREIGN PATENTS i.

-41o,431 Germany Feb. 24, 19,25

197,638 Great Britain 1,924 

1. A COMPOSITE ANODE COMPRISING A PAIR OF AXIALLY ALIGNED ELONGATED BLOCK-LIKE CONSUMABLE GRAPHITIC ELECTRODES EACH HAVING THE SAME OUTER SURFACE CONFIGURATION ALONG THEIR ENTIRE LENGTH AND HAVING FLAT END SURFACES, EACH ELECTRODE HAVING A BORE EXTENDING AXIALLY THERETHROUGH FROM END TO END, A THREADED COUNTER BORE EXTENDING INWARDLY FROM EACH END OF EACH ELECTRODE, THE THREADS OF THE COUNTER BORE OF CORRESPONDING ENDS OF THE ELETRODES BEING IDENTICAL, THE PITCH OF THE THREADS OF THE COUNTER BORE AT ONE END OF EACH ELECTRODE BEING IN THE SAME DIRECTION OF ROTATION BUT DIFFERENT IN PITCH THAN THE PITCH OF THE THREAD OF THE COUNTER BORE AT THE OTHER END OF THE ELECTRODE, A THREADED SOLID GRAPHITE NIPPLE, SAID NIPPLE 